php：检测浏览器语言

function get_client_language($availableLanguages, $default='en'){      if (isset($_SERVER['HTTP_ACCEPT_LANGUAGE'])) {          $langs=explode(',',$_SERVER['HTTP_ACCEPT_LANGUAGE']);          foreach ($langs as $value){              $choice=substr($value,0,2);              if(in_array($choice, $availableLanguages)){                  return $choice;              }          }      }      return $default;  }